1. Field of the Invention
The present invention generally relates to plasma enhanced atomic layer deposition (PEALD), particularly to a method for forming a single-phase multi-element film by PEALD.
2. Description of the Related Art
A Si-based mono-element insulation film (i.e., a film containing Si as the metal element and another non-metal element bonded to each other) expressed as SiX (X═B, C, N, or O) such as SiO or SiN is deposited by atomic layer deposition (ALD) using, as a reactant, O2 or O3 for SiO and NH3 for SiN. The “mono-element” refers to a single non-metal element in addition to a metal element. Although depending on the type of reactant, a base substrate or a photoresist is vulnerable to deformation due to plasma damage caused when the mono-element Si-based insulation film is exposed to a plasma, and the etch selectivity of the mono-element Si-based insulation film is insufficient. From the above viewpoints, multi-element Si-based films are under development. The term “multi-element” refers to multiple non-metal elements in addition to a metal element. As a method of depositing a multi-element insulation Si-based film, an ALD laminate method is known such as those disclosed in US 2009/0209081 A1, wherein for a SiOC film, for example, a SiC sub-layer and a SiO sub-layer are alternately deposited repeatedly by ALD, thereby forming a laminate film of SiOC. Since the above method uses two different types of cycle (i.e., a cycle for a SiC sub-layer, and another cycle for a SiO sub-layer), more steps and more complicated operation are required as compared with a method using a single type of cycle.
One object according to an embodiment of the present invention is to provide a method for depositing a multi-element Si-based insulation film by ALD without laminating different sub-layers.
Any discussion of problems and solutions involved in the related art has been included in this disclosure solely for the purposes of providing a context for the present invention, and should not be taken as an admission that any or all of the discussion were known at the time the invention was made.